Referring Expressions: Definition

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Referring Expressions Definition

• Referring expressions are words or phrases, the
  semantic interpretation of which is a discourse
  entity (also called referent)
• Discourse entities are semantic objects and they
  can have multiple syntactic realizations within a
  text
• Discourse entities live in the domain D, where a
  text is interpreted

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Referring Expressions Example

• A pretty woman entered the restaurant. She sat at
  the table next to mine and only then I recognized
  her. This was Amy Garcia, my next door neighbor
  from 10 years ago. The woman has totally changed!
  Amy was at the time shy

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Pronouns vs. Full NP

• A pretty woman entered the restaurant. She sat at
  the table next to mine and only then I recognized
  her. This was Amy Garcia, my next door neighbor
  from 10 years ago. The woman has totally changed!
  Amy was at the time shy

4
Definite vs. Indefinite NPs

• A pretty woman entered the restaurant. She sat at
  the table next to mine and only then I recognized
  her. This was Amy Garcia, my next door neighbor
  from 10 years ago. The woman has totally changed!
  Amy was at the time shy

5
Common Noun vs. Proper Noun

• A pretty woman entered the restaurant. She sat at
  the table next to mine and only then I recognized
  her. This was Amy Garcia, my next door neighbor
  from 10 years ago. The woman has totally changed!
  Amy was at the time shy

6
Modified vs. Bare head NP

• A pretty woman entered the restaurant. She sat at
  the table next to mine and only then I recognized
  her. This was Amy Garcia, my next door neighbor
  from 10 years ago. The woman has totally changed!
  Amy was at the time shy

7
Premodified vs. postmodified

• A pretty woman entered the restaurant. She sat at
  the table next to mine and only then I recognized
  her. This was Amy Garcia, my next door neighbor
  from 10 years ago. The woman has totally changed!
  Amy was at the time shy

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More NP types

• Inferrables
• He bought a used car. The engine is rather
  noisy.\
• Discontinuous sets
• John has known Bill for many years now. They
  often go hiking together.

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A more intriguing coloring

• A pretty woman entered the restaurant. She sat at
  the table next to mine and only then I recognized
  her. This was Amy Garcia, my next door neighbor
  from 10 years ago. The woman has totally changed!
  Amy was at the time shy

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Referring Expressions Definition

• Referring expressions are words or phrases, the
  semantic interpretation of which is a discourse
  entity (also called referent)
• Discourse entities are semantic objects and they
  can have multiple syntactic realizations within a
  text
• Discourse entities live in the domain D, where a
  text is interpreted

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Referring expressions and discourse referents
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Centering theory

• (Gro 1995) examines interactions between local
  coherence and the choice of referring expressions
• A pretty woman entered the restaurant. She sat at
  the table next to mine
• A woman entered the restaurant. They like
  icecream.

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Crash course 1 Centering theory. Motivation

• (Gro 1995) examines interactions between local
  coherence and the choice of referring expressions
• Pronouns and definite descriptions are not
  equivalent with respect to their effect on
  coherence
• They make different inference demands on the
  hearer or reader.

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Crash course 1 Centering theory. Definitions

• The centers of an utterance are discourse
  entities serving to link the utterance to other
  utterances
• Forward looking centers a ranked list
• A backward looking center
• Centers are semantic objects, not words, phrases,
  or syntactic forms but they are realized by such
  in the utterance

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Anaphora resolution

• Finding in a text all the referring expressions
  that have one and the same denotation
• Pronominal anaphora resolution
• Anaphora resolution between named entities
• Full noun phrase anaphora resolution

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Pronominal anaphora resolution

• Rule-based vs statistical
• (Ken 1996), (Lap 1994) vs (Ge 1998)
• Performed on full syntactic parse vs on shallow
  syntactic parse
• (Lap 1994), (Ge 1998) vs (Ken 1996)
• Type of text used for the evaluation
• (Lap 1994) computer manual texts (86 accuracy)
• (Ge 1998) WSJ articles (83 accuracy)
• (Ken 1996) different genres (75 accuracy)

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Continued

• Generic vs specific reference
• 1. The Vice-President of the United States is
  also President of the Senate.
• 2. Historically, he is the Presidents key man in
  negotiations with Congress
• 3a. He is required to be 35 years old.
• 3b. As Ambassador to China, he handled many
  tricky negotiations, so he is well prepared for
  the job